Cellular communications systems typically provide interconnect and/or dispatch voice communication services. Interconnect voice communication services are those typically provided by most cellular carriers as circuit-switched communications. As is known, dispatch communications are half-duplex communications where only one person at a time is able to speak. Dispatch communication services are commonly known as a push-to-talk (PTT) or walkie-talkie type of call, such as Sprint Nextel's service identified by the trade name Direct Connect. One type of network that supports both interconnect and dispatch communications is the Integrated Digital Enhanced Network (iDEN). In the iDEN network, dispatch communications are supported by dispatch application processors (DAPs).
In the current iDEN network as provided by Motorola, when a DAP enters its highest central processing unit (CPU) Load Shedding Level (Level 1), all dispatch call requests are rejected by the DAP, including dispatch calls that are originated by high priority callers, e.g., public safety agencies. This can be counterproductive during an emergency since, whereas public safety agencies may have the ability to acquire a dispatch channel at the radio frequency (RF) layer due to having a higher RF priority, the public safety agency may still be unable to initiate or receive dispatch calls due to the DAP(s) being in a CPU Load Shedding mode of operation. Therefore, even though high priority callers may have the ability to make a dispatch call due to their higher priority, the DAP systematically rejects calls from even these callers when operating in Load Shedding Level 1.
High priority callers, particularly public safety agencies, should have the ability to initiate and receive dispatch calls even when the DAP is in its highest CPU Load Shedding Level (Level 1). Therefore, there is a need for a method and system to allow for priority handling of dispatch call requests even when the dispatch network is in an operational mode where all call requests are normally rejected.